Synaptic connectivity constitutes an integral part of neuronal identity. The recent reconstruction of the connectome of the C.elegans male and its comparison to the long known connectome of the hermaphrodite (a derived female) reveal a sexually dimorphic dimension of neuronal identity: Some defined neuron types that are present in both hermaphrodites and males show sexually dimorphic synaptic connectivity patterns. We propose to dissect the regulatory programs that specify sexual dimorphic identity, as manifested by dimorphic synaptic connectivity features. Specifically, we propose here to (1) reliably and easily visualize sexually dimorphic synaptic connectivity patterns in transgenic animals using GFP-based reporter systems; (2) study aspects of the establishment, maintenance and autonomy of these dimorphic synapses and (3) identify molecules through a candidate gene approach and unbiased profiling approach that genetically program these dimorphic patterns of connectivity and identity. We expect that our studies will provide novel insights into the currentl little explored sexual dimension of neuronal identity.